Mechanistic Studies on α-Trifluoromethylation of Ketones via Silyl Enol Ethers and Its Application to Other Carbonyl Compounds

Synthesis of α-CF3 carbonyl compounds has been recognized to be difficult up to now because the polarization of CF3δ−-Iδ+ is opposite to that of CH3δ+-Iδ−, and this makes it difficult to introduce CF3+ unit to enolates. We recently reported an effective α-trifluoromethylation of ketones by using Et2Zn with Rh catalyst, but the mechanism has not fully been cleared. Now, we carried out the detailed mechanistic studies and found the involvement of a highly reactive alkylrhodium complex which derived from Et2Zn and RhCl(PPh3)3 in this α-trifluoromethylation. Furthermore, this α-trifluoromethylation was applied to other types of carbonyl compounds in good yields.